Honors Theses


Ryan McEwan, Ph.D.



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Honors Thesis


The biology of small, forested streams is critical to the ecology of larger waterways and broader watershed function. Because of their size, these “headwater streams” are strongly influenced by surrounding landscape conditions and their biology is intimately connected to the landscape through material and energy subsidies. In the United States, 50 to 80 percent of streams are primary headwater streams, making them a high priority for conservation. Often, stream salamanders are a useful indicator for biotic integrity of headwater streams due to their longevity, relatively stable populations, small home ranges, and abundance. Assessing stream salamanders is a challenging endeavor and existing methods often underestimate the abundance of salamanders present. In this project, we sought to develop and assess a new method for estimating salamander density in headwater streams. Our goal was to develop a device that mimics the habitat that salamanders prefer, leading to rapid colonization that also (a) represents a known area for estimating density and (b) is easy to handle for rapid assessment. The project sought to meet the following three aims: Aim1 invent a prototype device for quantification of salamander density in Ohio streams, Aim2 validate this prototype through field trials and against other methods, and Aim3 validate this prototype in various headwater streams and seasons. Field trials revealed that this method was superior for estimating salamanders than other methods including the standard Visual Encounter Survey (VES) and allows for estimation of population density. After placing the artificial habitat in a variety of streams through multiple seasons, we found that stream salamanders will colonize the apparatus and we can estimate a fair density of salamanders present in streams.

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Undergraduate research



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